Many quality control procedures call for the use of transport apparatus for transporting magnetic diskettes, also known as floppy disks, one after the other from a stack to appparatus which operates on the diskette such as a certifier which evaluates or certifies the disks in the diskettes. The apparatus then retrieves each such diskette from the certifier and routes it to one of two storage locations depending upon whether the diskette passed or failed evaluation or certification. One such transport apparatus is disclosed in applicant's copending application Ser. No. 460,316, filed Jan. 24, 1983 entitled DISKETTE SEQUENTIAL TRANSPORT APPARATUS.
The usual diskette comprises a plastic or cardboard envelope inside of which is positioned a flexible magnetic disk. See, for example, U.S. Pat. No. 3,668,658. Most diskettes in present day use have 5.25 inch diameter disks, those having largely replaced the earlier diskettes with 8 inch disks. The apparatus described in the above application is capable of handling such diskettes and effectively transporting them from a stack to a disk drive and retrieving them from the drive.
Recently, however, an even smaller storage medium known as a microdisk has been developed which has a disk that is only about 3 inches in diameter, yet carries the same amount of data as the 5.25 inch diskette. In our microdisk version, manufactured by Sony Corporation of Japan, the disk is contained in a rigid plastic case which is only 3.7 inches long, 3.54 inches wide and 0.125 inch thick. Its hub is exposed through apertures in the side of the case and one side of the case has a sliding window which is opened when the microdisk is seated in the disk drive to expose the disk to the drive's read/write head. The small size and weight of this new microdisk make it more difficult to feed the disk one after the other from a stack to a disk drive or other destination reliably on a high-speed basis. When being transported by prior apparatus, including the one described in my above pending application, the microdisk may become hung up on their way from the stack to their destinations. If unsupported, their paths may be affected by air currents. In some cases, due to the small size of the disks, the prior machines may feed a microdisk before the preceding disk has cleared the feed path or they may pick off more than one disk from the stack so that the machines jam, resulting in excessive downtime and high maintenance costs.
Also, the distances traveled by the microdisks in the prior transports tend to be rather long, resulting in a lower throughput for those machines. Additionally, the machines tend to be rather large and bulky so that they occupied a relatively large amount of table or floor space. Bearing in mind that a typical installation may require many such transports to certify or otherwise process the disk output for that installation, the overall floor space devoted to support and service the prior transports can become quite large.
The prior machines are disadvantaged in other respects. Some are relatively complex and costly to make and assemble. Some are excessively noisy so that, when a large number of such machines are located in a closed space, workers in the area are bothered by the din. Some prior transports have a relatively long cycle time. This is not only due to the long travel path of the microdisks as discussed above, it is also due to the mechanical and timing tolerances built into those machines to minimize malfunctions and jamming.